The long term goal of this research is to understand the molecular events underlying eukaryotic gene expression. The genes I will investigate are the family of sequences coding for histone proteins in the sea urchin embryo. Early in embryogenesis these genes are selectively activated and then undergo a shift in gene activity. This results in a new class of histone genes being active in later embryogenesis. This research proposal intends to provide a structural comparison between histone genes active in early embryogenesis and those active in later development. This will be accomplished by cloning procedures, restriction enzyme analysis, DNA renaturation and both RNA and DNA sequence analysis. Finally, the evolution of a histone gene will be examined by a complete sequence analysis of the histone H4 gene in two different sea urchin species. This should determine precisely how the translated and untranslated portions of a gene have evolved between species and provide the background for our understanding of how early and late histone genes have evolved within the cell.